A driving circuit having a function of precisely turning on and off a MOS transistor in a ground potential difference has been well known and is disclosed, for example, in Japanese Patent Publication (Kokai) No. H10-22803.
The driving circuit disclosed in Japanese Patent Publication (Kokai) No. H10-22803 is constituted with an npn-transistor and a resistor. The driving circuit turns on and off the MOS transistor corresponding to a voltage of an input terminal grounded and opened by a switching element located in a control circuit side.
The voltage of the input terminal for turning on the MOS transistor is set on high by changing a resistance. Accordingly, the MOS transistor is precisely turned even when the ground potential in the control circuit side becomes higher than ground potential in the driving circuit side.
However, the driving circuit disclosed in Japanese Patent Publication (Kokai) No. H10-22803 merely has the same input voltage at both turning on and turning off of the MOS transistor and fails to disclose hysteresis characteristics.